Various techniques have heretofore been used to shorten the time required for color development, i.e., to permit rapid color development. For example, a method has been widely used in which a penetrating agent, e.g., benzyl alcohol, is added to a color developer in order to permit rapid color development, since the penetration of a color developing agent into a light-sensitive material tends to be slow because of the poor hydrophilic nature of the color developing agent. In accordance with this method, however, sufficient coloration cannot be attained unless the color development processing is performed for at least 3 minutes at 33.degree. C.
In addition, a method comprising increasing the pH of a color developer is known. This method, however, suffers from various disadvantages; for example, when the pH is increased to more than 10.5, the oxidation of a color developing agent is seriously accelerated; since there is no suitable buffer, changes in the pH easily occur, and stable photographic properties cannot be obtained; and dependence on the processing time is increased.
It is also known to raise the activity of a color developer by increasing the concentration of a color developing agent therein. In this method, however, problems arise in that the processing solution is comparatively high in cost since the color developing agent is very expensive, and that the color developing agent readily precipitates, making the processing solution instable. Thus this method is not suitable for practical use.
In order to accomplish color development rapidly, there is known a method in which a color developing agent is previously incorporated into a light-sensitive material. For example, U.S. Pat. No. 3,719,492 discloses a method in which a color developing agent is incorporated as a metal salt. In accordance with this method, however, the resulting light-sensitive material is poor in storage stability and may be fogged prior to use thereof, and, furthermore, fogging may readily occur during color development.
It is also known, as is described in U.S. Pat. No. 3,342,559 and Research Disclosure, No. 15159 (1976), that in order to inactivate the amine moiety of a color developing agent, it can be incorporated in the form of a Schiff base. In this method, however, color development can proceed only after the color developing agent is alkali-hydrolyzed, and the color development is rather retarded. In incorporating the color developing agent as such, problems arise in that an emulsion is fogged during the storage thereof since the color developing agent is unstable, and, furthermore, various problems are involved in effecting the processing since the film-forming property of the emulsion is decreased.
Furthermore, it is known, as described, for example, in L. F. A. Mason, Photographic Processing Chemistry, Focal Press, pp. 103-107 (1966), that a compound represented by formula (I) as described hereinafter can be added to a black-and-white developer containing a developer, e.g., hydroquinone, to accelerate development. Incorporation of such compounds into a light-sensitive material is described in British Pat. No. 767,704. In the British Patent, however, the compounds are incorporated into a black-and-white light-sensitive material or a reversal color photographic light-sensitive material, for the purpose of accelerating only black-and-white development, and it is not intended at all to accomplish color development within a short time, such as 1 minute.
Japanese Patent Application (OPI) No. 52422/78 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") discloses the incorporation of the compound of formula (I) as described hereinafter into a color photographic light-sensitive material which contains a 2-equivalent magenta coupler having an oxy type of organic split-off group at an active site, for the purpose of preventing a reduction in the sensitivity of the color photographic light-sensitive material in the unexposed state. In Japanese Patent Application (OPI) No. 52422/78, however, no consideration was given to performing a rapid processing within a period of 1.5 minutes or less. Furthermore, it has been found that when the above-noted 2-equivalent magenta coupler is used, the effects of the invention as described hereinafter cannot be obtained, and a reduction in the photographic properties of the light-sensitive material containing the coupler occurs with a lapse of time.
A method of color developing a color photographic light-sensitive material by the use of a color developer containing a compound falling within the scope of the definition of formula (I) as described hereinafter is also known as described in British Pat. No. 1,032,925. In this method, however, when the processing is performed under normal conditions, only black-and-white development proceeds, and almost no color image is obtained.